Meeting Abstract
Urban translocation success of native species is often low because of habitat degradation due to invasive species, lack of phenotypic variability, and differences between source and release environments. We marked and released 327 American Toads (Anaxyrus americanus) raised under different experimental conspecific densities (10 or 29 tadpoles/tank) and hydroperiods (60, 75, or 90 days) to a 12-acre wooded suburban park with a manmade pond. Introduction success was expected to increase with body mass if selection was strongest against individuals vulnerable to resource deprivation (low moisture or food levels). Alternately, introduction success was expected to increase with jumping distance if selection was strongest against toads unable to escape predators by jumping. Time to metamorphosis was highest in the 75-day hydroperiod, with a greater effect at low density (significant hydroperiod*density interaction, ANOVA, p=0.0017). Body size (snout-vent length, leg length, and mass) at metamorphosis significantly increased with density (ANOVA, p<0.0001, p<0.0001, p=.0052 respectively). Survival rate through metamorphosis was highest in the higher density with a significant interaction between density and hydroperiod (ANOVA, p= 0.0311 and p=0.0175 respectively). Similar to our first (unsuccessful) introduction attempt of 670 toads in 2016, recapture success this year has been very low. Generating different phenotypes may increase introduction success, however, poor habitat quality, priority effects (green frog predation), and relatively low numbers for an introduction attempt still present difficulties in experimentally studying and restoring urbanized habitats.
